Hydrogen dynamics in solids : quantum diffusion and plastic phase transition in hydrates under pressure ; Dynamique de l'hydrogène dans les solides : diffusion quantique et transition de phase plastique dans les hydrates sous pression
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| Title: | Hydrogen dynamics in solids : quantum diffusion and plastic phase transition in hydrates under pressure ; Dynamique de l'hydrogène dans les solides : diffusion quantique et transition de phase plastique dans les hydrates sous pression |
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| Authors: | Avallone, Niccolo |
| Contributors: | Institut des Nanosciences de Paris (INSP), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Sorbonne Université, Fabio Finocchi, Riccardo Spezia, Simon Huppert |
| Source: | https://theses.hal.science/tel-04514995 ; Materials Science [cond-mat.mtrl-sci]. Sorbonne Université, 2023. English. ⟨NNT : 2023SORUS622⟩. |
| Publisher Information: | CCSD |
| Publication Year: | 2023 |
| Subject Terms: | Quantum Algorithms, Proton dynamics, Nuclear Quantum Effects, Algorithmes quantiques, Dynamique du proton, Effets quantiques nucléaires, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], [PHYS.COND.CM-SM]Physics [physics]/Condensed Matter [cond-mat]/Statistical Mechanics [cond-mat.stat-mech] |
| Description: | Atomic-scale simulations of ammonia hydrates pose major theoretical and numerical challenges for several reasons. The description of disordered and/or frustrated systems requires large-scale simulations (several thousand atoms on nanosecond time scales). This makes impossible to use ab initio methods to describe interatomic interactions. Moreovere, the presence of hydrogen leads to a highly complex phase diagram. The specific properties of hydrogen bonds between water and ammonia molecules explain the plasticity, proton jumps produce ionic phases, and at high pressures, the quantum behavior of protons is not negligible: the usual molecular dynamics approximation, which treats atomic nuclei as classical objects, is no longer valid. After a theoretical chapter on the simulation techniques used, the second chapter of this work deals with the problem of proton diffusion in a solid, taking nuclear quantum effects into account. Two main classes of molecular dynamics methods are compared, i.e. quantum bath methods (QTB/adQTB), based on the generalized Langevin equation, and methods derived from the quantum mechanical path integral formalism ((T)RPMD). The aim is to determine which method would be the most accurate and numerically the least expensive for studying proton hopping and diffusion in ammonia hydrates. The (T)RPMD method appears to approximately meet this objective, while the QTB/adQTB methods considerably overestimate diffusion. However, their low computational cost does not completely exclude them from the study of the quantum properties of these systems. The third chapter presents a theoretical study of the crystal-plastic phase transition in ammonia hemihydrate, between 2GPa and 10GPa, and between 300K and 600K. The experimental results show the appearance of plastic and disordered phases, although they do not provide a complete explanation of the mechanisms behind the phase transitions. We mainly use classical molecular dynamics, coupled with force fields, to simulate 100,000 atoms on time scales of tens ... |
| Document Type: | doctoral or postdoctoral thesis |
| Language: | English |
| Relation: | NNT: 2023SORUS622 |
| Availability: | https://theses.hal.science/tel-04514995 https://theses.hal.science/tel-04514995v1/document https://theses.hal.science/tel-04514995v1/file/140701_AVALLONE_2023_archivage.pdf |
| Rights: | info:eu-repo/semantics/OpenAccess |
| Accession Number: | edsbas.615468A2 |
| Database: | BASE |
Nájsť tento článok vo Web of Science | Abstract: | Atomic-scale simulations of ammonia hydrates pose major theoretical and numerical challenges for several reasons. The description of disordered and/or frustrated systems requires large-scale simulations (several thousand atoms on nanosecond time scales). This makes impossible to use ab initio methods to describe interatomic interactions. Moreovere, the presence of hydrogen leads to a highly complex phase diagram. The specific properties of hydrogen bonds between water and ammonia molecules explain the plasticity, proton jumps produce ionic phases, and at high pressures, the quantum behavior of protons is not negligible: the usual molecular dynamics approximation, which treats atomic nuclei as classical objects, is no longer valid. After a theoretical chapter on the simulation techniques used, the second chapter of this work deals with the problem of proton diffusion in a solid, taking nuclear quantum effects into account. Two main classes of molecular dynamics methods are compared, i.e. quantum bath methods (QTB/adQTB), based on the generalized Langevin equation, and methods derived from the quantum mechanical path integral formalism ((T)RPMD). The aim is to determine which method would be the most accurate and numerically the least expensive for studying proton hopping and diffusion in ammonia hydrates. The (T)RPMD method appears to approximately meet this objective, while the QTB/adQTB methods considerably overestimate diffusion. However, their low computational cost does not completely exclude them from the study of the quantum properties of these systems. The third chapter presents a theoretical study of the crystal-plastic phase transition in ammonia hemihydrate, between 2GPa and 10GPa, and between 300K and 600K. The experimental results show the appearance of plastic and disordered phases, although they do not provide a complete explanation of the mechanisms behind the phase transitions. We mainly use classical molecular dynamics, coupled with force fields, to simulate 100,000 atoms on time scales of tens ... |
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